Beverage container lids adapted to fasten over the rim or lip of disposable beverage containers are well known. Such lids reduce spillage and evaporation of the beverage within the container and help insulate the contents of the container from the external ambient temperature. In their most simple form, such beverage container lids comprise a generally flat lid surface in the form of a disk having a peripheral sealing skirt for securing the lid to the rim of the beverage container. While such lids are entirely suitable for the purposes just described, they must be completely removed in order to gain access to the contents of the container.
This problem has been substantially reduced for cold beverages by providing a selectively opened straw orifice in the lid. This allows access to the contents of the container without removing the lid. Unfortunately, the use of a straw for hot beverages such a coffee or hot chocolate is generally not preferred.
Improved container lids for hot beverages which include an openable tear strip or flap have been devised. See for example U.S. Pat. Nos. 3,868,043, 3,977,559, 4,090,660, and 4,210,272. Such modified beverage container lids offer the advantage of allowing limited access to the contents of the container while still covering most of the open end of the container. However, this type of lid has the disadvantage of providing a direct path from which the beverage in the container can easily spill during use.
Further improvements have been made to the beverage container lids including fold back flaps, see U.S. Pat. Nos. 3,994,411, 4,202,459, 4,322,015, 4,473,167, 4,629,088, 4,738,373, 5,090,584, 5,111,961, 5,183,172, 5,197,624 and 5,613,619. These fold back flaps and various means for securing tear strip or flap in its fully folded back configuration have been provided. For example, U.S. Pat. No. 3,994,411 discloses a container lid having a fold-back flap which includes a pull tab along its outermost edge. The pull tab may be inserted into a slit along the outermost edge of the lid to hold the flap in its fully open position. U.S. Pat. No. 4,202,459 discloses an embossed slot formed in the upper surface of the lid which is able to receive the peripheral skirt of the lid when the flap is fully folded back. Finally, U.S. Pat. No. 4,322,015 discloses a container lid having a fold-back flap which is secured by one or more retainer studs which project upward from the upper surface of the lid. Although each of these designs is workable, there are several disadvantages, in particular, the openable flaps frequently become dislodged from their retaining means and are difficult to hold in the open position. In the case of recloseable flaps, they often do not adequately seal the opening when closed and are difficult to hold in the closed position. Moreover, it is frequently necessary to employ relatively heavy gauge or stiff materials in order to achieve a highly reliable fastening system which is more expensive. Another disadvantage results when the flaps do not tear accurately along the intended line and form sharp edges at each side of the opening thereby formed in the rim or skirt of the container lid which causes discomfort during use. Furthermore, once the flap has been released the lid edges on either side of the opening are difficult to secure to the container lip and do not make an adequate seal allowing the contents of the container to spill from these edges during normal use.
A number of lids have been developed that prevent spillage of the liquid inside the container by utilizing constructions that produce, or create, an anti-siphoning effect such as those described in U.S. Pat. Nos. 2,456,989 and 4,915,250. Unfortunately, these types of lids require the user to apply suction to draw fluid through the drinking opening. While this may be acceptable for cold liquids it can be dangerous if a large volume of hot liquid is inadvertently drawn into the mouth causing scorching.
Another device described in U.S. Pat. No. 4,394,928 is a combination cup and cover that utilizes passages provided in the cover that join with a shelf provided in the container to form an enclosed fluid path from the inside of the container to the drinking opening. Unfortunately, this device requires both the container and the lid to create a functioning fluid path. Neither the lid nor the container can provide spill protection by itself. The major disadvantage of this device is that the lid cannot be used with existing commercially available containers, consequently, the combination container and cover must be sold as a unit not separately.
Consequently, a lid which does not have to be removed from the beverage container, does not suffer from the disadvantages discussed above and significantly reduces or prevents spillage during normal use is needed.